diffusion

osmosis

the diffusion of water from an area of high concentration to an area of lower concentration across as selectively permiable cell membrane; no energy required and stops at equilibrium; this type of transport is passive transport

active transport

the movement of particles from areas of low concentration to higher concentration and requires energy; can be described when someone is biking up a hill they are going from low to high and need energy to do this

passive transport

the movement of particles from areas of high concentration to lower concentration and does not require any energy; can be described when someone is going down a hill, from high to low, and they do not need energy because they are just coasting; examples of passive transport are osmosis and diffusion

What animal cells need and don't need

Some #'s from the homework

Q: Why is small size an advantage to a cell?
A: Small size is an advantage to a cell for a couple of reasons:
1) It allows materials to travel more quickly in the streams of cytoplasm, effectively reducing waste and creating important functions so the cell can survive.
2) If cells were large, then if one cell died you would lose something big, like a body part! But, because cells are so small, when one cell dies, you are not majorly affected by its loss.
Q: What will happen to a cell that is put into a tank of salt water?
A: The cell will change because outside of the cell, the concentration of salt molecules is higher than that of water molecules. So, the water in the cells go from a high concentration inside the cell to a low concentration outside of cell, the happening of osmosis. Because water is leaving the cell the cell will shrink.

More about cells

~When a cell swells and bursts, this is called: Lyse
~When a cell shrinks and crumples, this is called: crenate
~Water Molecules can move through a selectively permiable membrane, while glucose molecules cannot.
~In order to understand the affect on osmosis on a cell or a selectively permiable membrane you must understand:
- the concentration of water molecules and any other substance inside and outside of the cell.
- You must also understand that if there is a higher concentration of water outside of the cell, due to scientific computation the higher concentration of water will move to the lower concentration inside the cell, effectively causing the cell to swell. The situation can also be vice-versa.

Potato Mini-lab- What and why has it occured?

Our group figured out that the potato slices were placed into two different liquids, because one had a rough, stiff shape, while the one in the other beaker has a smooth, flexible shape. So, we concluded the the harder potato slice was placed into tap water, while the softer potato slice had been placed into salt water. What happened with the smaller potato slice is that because the concentration of water molecules inside the cell was greater than in the salt water, osmosis occurred and the water molecules in the higher concentration were tranported to the lower concentration of molecules, effectively shrinking the cell because of its loss of water. For the other beaker, what happened was because the higher concentration of water molecules were in the water outside of the potato, the molecules in the water transported to the ones in the cell, effectively causing the cell to swell because of its increase in water.

Some questions from the lab.......

Name two gases that diffuse in and out of the cell.
~Two gases are carbon dioxide and oxygen.
Can the molecule C6H1206 pass through a cell membrane?
~ No, because this substance is almost identical to glucose and glucose cannot pass through a selectively permiable membrane.
What do we call a membrane that is permiable to some substance but no to others?
~ selectively permiable membrane